A recent incident during which staff at the Centers for Disease Control and Prevention was potentially exposed to anthrax is part of a larger pattern of “an insufficient culture of safety,” Director Thomas R. Frieden told a panel of House lawmakers Wednesday.

Frieden faced sharp questions from Republicans and Democrats about how the June incident and other episodes such as the shipment of influenza strains contaminated with a deadly flu virus to a Department of Agriculture laboratory were able to happen, as well as what steps are being taken to prevent future problems. Pennsylvania Republican Tim Murphy, chairman of the Energy and Commerce Oversight and Investigations Subcommittee, called the lapses sloppy and inexcusable. And Diana DeGette of Colorado, the top Democrat on the panel, said it was “an alarming series of failures.”

Lawmakers also expressed interest in a Government Accountability Office proposal to put an entity in charge of a national strategy for high-containment laboratories that study hazardous pathogens. The GAO said such a move would probably require congressional action.

Murphy asked for additional details about what that would look like, but Nancy Kingsbury, managing director of applied research and methods for GAO, said she didn’t have specifics. The agency would likely need to work with congressional staff to talk through some of the options, she said.

Texas Democrat Gene Green also asked if CDC has received adequate congressional funding to carry out its safety mission, but Frieden said he does not think the primary issue is a lack of money. Instead, he emphasized the need to strengthen the culture of safety at the agency, noting that he thinks scientists who work with something every day have a level of familiarity that could lead to slip ups.

“While we have scientists who are the best in the world at what they do, they have not always applied that same rigor that they do to their scientific experiments to improving safety,” he said.

Frieden said that he has placed a moratorium on transferring biological material out of the agency’s labs with the highest-risk microbes. He also noted that the two affected laboratories have been closed and will not be reopened until both he and the Animal and Plant Health Inspection Service are confident they’re safe.

In addition, Frieden said that he appointed Michael Bell, a senior scientist, to report directly to him and serve as the point person on the issue. Other steps include convening a high-level working group within the agency and an external advisory group of outside experts.

“What happened was completely unacceptable,” Frieden said at the outset of his testimony. “It should never have happened.”

But Republicans argued that many of the actions that CDC plans to take are similar to measures described by Frieden in a letter responding to committee concerns about laboratory safety in 2012. Mississippi Republican Gregg Harper asked for the name of the senior official who the letter said would be designated to report to the director on safety issues – which Frieden said he would provide later – and questioned how Bell’s appointment would be more effective.

Frieden said the agency addressed specific problems that were identified in 2012, such as concerns about air flow and security, but missed the broader patterns that Bell is now overseeing.

Jere Dick, associate administrator of the Animal and Plant Health Inspection Service, also provided testimony since his agency began oversight of the CDC in 2012. Frieden said he decided to turn the inspection process over to the Agriculture Department at that time because he was concerned that there was the appearance that the agency could not be objective in inspecting its own laboratories.

At the close of the panel, DeGette said she hoped the subcommittee would have the witnesses back in the fall after Frieden completes the investigation.